relation - an abstraction belonging to or characteristic of two entities or parts together

forerunner, antecedent - anything that precedes something similar in time; "phrenology was an antecedent of modern neuroscience"

chronology - arrangement of events in time

synchroneity, synchronicity, synchronisation, synchronism, synchronization, synchronizing, synchrony - the relation that exists when things occur at the same time; "the drug produces an increased synchrony of the brain waves"

asynchronism, asynchrony, desynchronisation, desynchronization, desynchronizing - the relation that exists when things occur at unrelated times; "the stimulus produced a desynchronizing of the brain waves"